Evening Primrose Oil: Benefits, Side Effects, and Dosage

Evening primrose (Oenothera biennis) is a flowering plant that blooms at night, hence its name. Although the plant is native to North and South America, it also grows in Europe and Asia.

What makes evening primrose oil popular are the multiple health claims touted for its use. It was so popular that in the 17th century, it was dubbed “King's cure-all” in Europe. It has been around for a long time as a folk remedy, and it is suggested to help ease skin conditions, menstrual symptoms, or inflammation.

Here's what you should know about evening primrose oil: how it is made, its benefits and uses, as well as the side effects and risks associated with its consumption.

What is evening primrose oil?

Evening primrose oil (EPO) is a plant-based oil derived from the seeds of the evening primrose plant. The seed oil is obtained through a cold-pressing extraction process to preserve high levels of its constituents, beneficial compounds, and essential fatty acids.

Commonly used in the form of oral supplements and topical applications, EPO is rich in gamma-linolenic acid (GLA), an omega-6 fatty acid known for its anti-inflammatory properties, which is believed to be EPO's main active compound.

As such, many companies have developed pure GLA supplements as well. Research on EPO's effectiveness for various health conditions is ongoing, warranting consultation with a healthcare professional before use.

5 evening primrose oil benefits

From nurturing skin health to alleviating hormonal imbalances, EPO is believed to offer a spectrum of potential benefits.

Here's a breakdown of the five evening primrose oil benefits according to research:

1. May improve overall skin health

Many believe evening primrose oil promotes overall skin health in a few ways. Its anti-inflammatory properties were suggested to help alleviate symptoms of eczema, potentially offering some relief for those experiencing flare-ups. However, a 2013 review and meta-analysis provided a contradictory conclusion stating that EPO failed to improve global eczema symptoms when taking into account findings from 19 clinical studies.

Furthermore, the GLA content in EPO may contribute to maintaining a healthy skin barrier, which can help retain moisture and promote overall skin hydration. A 2005 study in healthy adults found that evening primrose oil could improve skin moisture, trans-epidermal water loss, elasticity, firmness, fatigue resistance, and roughness after 12 weeks. However, it's important to note that the evidence for some of these benefits is still being explored.

2. May help relieve PMS symptoms

Pre-menstrual syndrome (PMS) symptoms include headaches, mood swings, insomnia, acne, breast tenderness, fatigue, depression, and neuropathic pain. Some studies suggest that EPO might be a natural remedy for PMS. The body can convert GLA into hormone-like molecules and may potentially influence PMS symptoms, but EPO's potential as an herbal treatment to relieve PMS symptoms is another topic of ongoing research with mixed results.

A 2010 clinical trial suggests that an EPO supplement (which also contains Vitamin E and B6) is beneficial for PMS. In 2019, a review article assessed the studies conducted on evening primrose oil for women's ailments and found that EPO may help with PMS, but according to the authors, the effects are not immediate and may be expected from regular use for around 4-6 months. A 2021 systematic review and meta-analysis of 13 trials with 1,752 patients with PMS found that EPO is beneficial against mastalgia (breast pain).

3. May reduce hot flashes in menopausal women

EPO is a popular product in menopausal women. However, the exact mechanism by which EPO might reduce hot flashes in menopausal women remains under examination, but some potential explanations exist. Similar to the previous explanations, GLA in EPO can be converted by the body into prostaglandin E1 (PGE1), which has a crucial role in regulating body temperature.

During menopause, declining estrogen levels can disrupt the production of prostaglandins. Therefore, the increased PGE1 levels from EPO's GLA may help regulate core body temperature, potentially leading to fewer and less intense hot flashes. Additionally, individual responses to EPO can vary.

In 2013, a 6-week clinical trial on 56 menopausal women, found that evening primrose oil may help decrease the intensity of hot flashes and the HFRDIS (hot flash-related daily interference scale) score.

This 2019 review also supports the potential of evening primrose oil for hot flashes in menopausal women. Another systematic review and meta-analysis in 2020 published the overall beneficial effects of EPO on menopausal symptoms.

A more recent 2023 clinical trial assessing a product containing evening primrose oil (along with hop extract, saffron, tryptophan, vitamins B6, D3, K2, B12, and B9) found a beneficial effect on reducing menopausal hot flashes.

4. May reduce symptoms of rheumatoid arthritis

EPO is also being used as a natural remedy for rheumatoid arthritis (RA) symptoms. RA is an autoimmune condition characterized by chronic joint inflammation, wherein the body's immune system mistakenly attacks its own tissues, leading to pain, swelling, and stiffness in the joints.

Due to its high GLA contents, it might offer relief through anti-inflammatory effects and potential regulation of prostaglandins, which are mechanisms that play a role in RA inflammation. This way, GLA may help mitigate the inflammatory processes underlying RA, which may be used for chronic pain management.

However, more research is needed to confirm its effectiveness. Based on a recent systematic review of relevant clinical trials (2024), the results are inconclusive, wherein some studies found significant benefits of evening primrose oil on rheumatoid arthritis while others did not.

5. May help improve heart health

EPO shows potential for heart health through its impact on cholesterol and inflammation. GLA in EPO may lower triglycerides, lower LDL ("bad") cholesterol and raise HDL ("good") cholesterol, while its anti-inflammatory properties could benefit cardiovascular health by helping mitigate chronic inflammation.

Based on this 2020 systematic review and meta-analysis of clinical trials evaluating the effect of evening primrose oil supplementation on lipid profiles, EPO was reported to reduce triglyceride levels and increase HDL levels. In an animal model of myocardial infarction with hypercholesterolemia, researchers found that EPO may ameliorate platelet aggregation and improve heart recovery. While more research is needed, preliminary studies suggest EPO as a complementary intervention in reducing cardiovascular disease (CVD) risk factors.

Side effects and risks of evening primrose oil

EPO is generally considered safe for most people when taken orally or applied topically in appropriate doses. However, some individuals may experience mild side effects, such as gastrointestinal discomfort, including nausea, diarrhea, or indigestion. Allergic reactions are rare but possible, particularly in individuals sensitive to plants in the Onagraceae family.

People with bleeding disorders or those taking anticoagulant medications should use EPO cautiously due to the potentially increased bleeding risk. Similarly, individuals with epilepsy should also exercise caution, as EPO may exacerbate these conditions.

Pregnant women should avoid EPO as it may stimulate uterine contractions, potentially leading to complications. It's essential to consult a healthcare professional before using EPO, especially if you have underlying health conditions or are taking medications, to ensure safety and efficacy.

Lastly, although the production and labeling of evening primrose oil may follow FDA regulations, the medicinal use of this product has not been approved by the FDA.

What medications should not be taken with evening primrose oil?

Evening primrose oil should be used cautiously with certain medications due to potential interactions.

It can increase bleeding risk when taken with anticoagulants (e.g., warfarin) or antiplatelet drugs (e.g., aspirin, clopidogrel) and nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen. EPO may also lower the seizure threshold, posing risks for those on anticonvulsants (e.g., carbamazepine, phenytoin) or certain antipsychotics (e.g., chlorpromazine).

Additionally, EPO could potentially interact with other medications metabolized by the liver. Therefore, it is crucial to consult a healthcare provider before combining EPO with these or any other medications to avoid adverse effects.

How to use evening primrose oil?

Evening primrose oil is used both orally and topically for various medical conditions.

For oral use, typical dosages are usually divided into smaller doses, depending on the condition being treated, while it is used topically, applied directly to the skin, for conditions like eczema or dry skin.

When to take evening primrose oil: morning or night?

EPO can be taken either in the morning or at night, as its benefits are not time-dependent. The choice depends on individual preference and tolerance. Some people may prefer taking it with meals aiming to enhance absorption and reduce gastrointestinal discomfort.

For conditions like premenstrual syndrome (PMS) or menopausal symptoms, dividing the daily dosage into smaller doses taken throughout the day may be beneficial. If using EPO to improve sleep quality or reduce nighttime symptoms, taking it in the evening might be more appropriate. Always consult with a healthcare provider to determine the best timing and dosage for your specific needs.


There is no standard dose for EPO. Nonetheless, the dose of the oil varies based on the condition being treated. For general health and maintenance, typical oral doses found on the market range from 500 to 2,000 mg daily, often divided into 2-3 doses taken with meals. Topical application usually involves using a few drops on the affected skin area once or twice daily. Always follow dosage recommendations provided by a healthcare professional and adjust based on individual response and tolerance.

Can you get evening primrose oil from foods?

No, you cannot obtain evening primrose oil directly from consuming food.

Dietary sources of GLA exist, but while it is found in some plant sources like borage seeds and black currants, the quantities are lower than those found in highly concentrated evening primrose oil supplements. Given the potential health benefits associated with EPO, reaching therapeutic levels through food consumption alone would be challenging.

Evening primrose oil vs other supplements

EPO is often compared to other natural oils and supplements due to its proposed benefits for skin health, inflammation, and hormonal issues.

Evening primrose oil vs borage oil

Borage oil has a higher GLA content compared to EPO, potentially making it more effective for these uses. Since both EPO and borage oil contain GLA, they are both proposed to be beneficial for inflammatory conditions, skin health, and premenstrual syndrome. Due to borage oil's higher GLA concentration, it may provide stronger anti-inflammatory effects compared to EPO. EPO is commonly used due to its well-established safety profile as compared to borage oil.

Evening primrose oil vs flaxseed oil

EPO and flaxseed oil differ in their primary active ingredients and benefits. Flaxseed oil does not have GLA, but contains alpha-linolenic acid (ALA), an omega-3 fatty acid that can support cardiovascular health, reduce inflammation, and aid in digestive health. Flaxseed is a good source of fiber and may offer additional digestive benefits. While both oils offer anti-inflammatory properties, EPO is proposed to be more effective for skin and hormonal conditions, whereas flaxseed oil might excel at cardiovascular and general anti-inflammatory support.


Evening primrose oil (EPO), derived from the seeds of the evening primrose plant, is known for its rich gamma-linolenic acid (GLA) content and its various potential health benefits, with historic use both orally and topically. Key benefits proposed include promoting skin health, alleviating PMS symptoms, reducing menopausal hot flashes, potentially easing rheumatoid arthritis symptoms, and improving heart health. While similar to other supplements like borage and flaxseed oils, EPO is particularly noted for its safety as well as its potential skin and hormonal health benefits due to its GLA content.

However, research findings on its effectiveness are mixed, necessitating further studies and consultation with healthcare providers before use. EPO is generally safe but can cause mild gastrointestinal issues and pose risks for individuals with specific health conditions or those taking certain medications. Proper dosage and timing, tailored to individual needs and health goals, are crucial for optimizing the health of those interested in using EPO.


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